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Author Topic:   Attaching Hardware to UniBond Hulls

nitro vinny posted 09-11-2010 03:17 PM ET (US)
On a 1970 17-foot Boston Whaler boat is the explaination given in the FAQ section of repairing loose rail anchors the recommended technique for anchoring Bimini top hardware attachment, especially the sliding rails atop the gunwales? As I will not be installing any of the original rails, my plan is to use the mounting wood areas to secure the forward and stern hold-down straps.
Or, will I need to route out strategically located slots to insert wood strips and fiberglass them in place?
What about securing cleats?
contender posted 09-11-2010 03:57 PM ET (US)
Nitro: are you talking about the eyelets for the Bimini top? I found it better to place the eyelets on the inside of the hull (I place mine about 2 inches below the top of the gunwale at a 45 degree angle). This gives the screws better holding capacity than having them pulling straight up. Place your t-top in the open position and where you want it to stand when open. (may need a friend to help with this to hold it in position). If you are using a track the t-top will slide to the end of the track (unless you have a stop in the track) for the set up. I have 4 adjustable straps for my t-top, so while your friend is holding the top in position mark your eyelet positions. You just need to mark one side then use measurements to make them the same on the other side of the boat. Also make sure you have extra length in your straps before drilling the eyelets in position (do not make the eyelets to far apart so that you do not have enough material reach with the straps). You can use a carpenters square to get the angle on the eyelets and use some 3m 5200 for the screw holes on the eyelets and on the track screws... What kind of cleats are you talking about? Do you want more places to tie off the boat?
jimh posted 09-11-2010 04:39 PM ET (US)
For using screw fasteners to hold down a track for a sliding canvas frame rail base, I would initially just install the self-tapping screws with care into the Unibond hulls. I would not try to drill out big holes and fill with an epoxy and filler mixture. If you carefully drill the pilot hole so as to maximize the purchase of the screw threads into the laminate, while at the same time making the hole in the gel coat layer larger so as not to get a crack, I think you will be able to obtain sufficient strength in the fasteners to retain the slide track base on the gunwale.
The suggestion in the FAQ about re-working loose fasteners is just for that--loose fasteners which have already worked and loosened themselves from the laminate layer.
nitro vinny posted 09-11-2010 07:31 PM ET (US)
contender and jimh: It still appears that the only grip a screw has is through the thin fiberglass layer of the top of the gunwale, or through the upper portion of the inside of the hull. I like a bit of over-engineering and don't see any possibility for that w/o a bit of extra effort.
contender posted 09-11-2010 10:38 PM ET (US)
Nitro: I always feel the same, I do not want to do it again, or have it come loose. I you are using a track you can place it on top of the gunnel (I placed stainless screws about 6 inches apart and one at each end of the track) I drilled very small pilot holes (as Jim stated) and then put a spot of 3m 5200 over each hole. The combination of the amount of screws and the 5200 will hold the track just fine. Do the same for the eyelets on the inside of the hull. I just redid my hull and the eyelets that hold my Bimini top have been in place since 1975(screwed to the inside of the hull). Like I said the trick is not pulling on the screws from the top, the force on the screws are from the side, they are much stronger this way. And having the eyelets at an angle (in-line) with the straps help also. I'll see if I can get you some pictures of my set up....Take care
Hoosier posted 09-12-2010 07:34 AM ET (US)
When I installed Bimini tracks on my Montauk I used a full length strip of auto trim tape on the bottom of the track, in addition to the screws. The tracks never moved or loosened.
nitro vinny posted 09-12-2010 03:03 PM ET (US)
Thanks for the 5200 and the auto trim tape pointers.

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Author	Topic: Attaching Hardware to UniBond Hulls
nitro vinny	posted 09-11-2010 03:17 PM ET (US) On a 1970 17-foot Boston Whaler boat is the explaination given in the FAQ section of repairing loose rail anchors the recommended technique for anchoring Bimini top hardware attachment, especially the sliding rails atop the gunwales? As I will not be installing any of the original rails, my plan is to use the mounting wood areas to secure the forward and stern hold-down straps. Or, will I need to route out strategically located slots to insert wood strips and fiberglass them in place? What about securing cleats?
contender	posted 09-11-2010 03:57 PM ET (US) Nitro: are you talking about the eyelets for the Bimini top? I found it better to place the eyelets on the inside of the hull (I place mine about 2 inches below the top of the gunwale at a 45 degree angle). This gives the screws better holding capacity than having them pulling straight up. Place your t-top in the open position and where you want it to stand when open. (may need a friend to help with this to hold it in position). If you are using a track the t-top will slide to the end of the track (unless you have a stop in the track) for the set up. I have 4 adjustable straps for my t-top, so while your friend is holding the top in position mark your eyelet positions. You just need to mark one side then use measurements to make them the same on the other side of the boat. Also make sure you have extra length in your straps before drilling the eyelets in position (do not make the eyelets to far apart so that you do not have enough material reach with the straps). You can use a carpenters square to get the angle on the eyelets and use some 3m 5200 for the screw holes on the eyelets and on the track screws... What kind of cleats are you talking about? Do you want more places to tie off the boat?
jimh	posted 09-11-2010 04:39 PM ET (US) For using screw fasteners to hold down a track for a sliding canvas frame rail base, I would initially just install the self-tapping screws with care into the Unibond hulls. I would not try to drill out big holes and fill with an epoxy and filler mixture. If you carefully drill the pilot hole so as to maximize the purchase of the screw threads into the laminate, while at the same time making the hole in the gel coat layer larger so as not to get a crack, I think you will be able to obtain sufficient strength in the fasteners to retain the slide track base on the gunwale. The suggestion in the FAQ about re-working loose fasteners is just for that--loose fasteners which have already worked and loosened themselves from the laminate layer.
nitro vinny	posted 09-11-2010 07:31 PM ET (US) contender and jimh: It still appears that the only grip a screw has is through the thin fiberglass layer of the top of the gunwale, or through the upper portion of the inside of the hull. I like a bit of over-engineering and don't see any possibility for that w/o a bit of extra effort.
contender	posted 09-11-2010 10:38 PM ET (US) Nitro: I always feel the same, I do not want to do it again, or have it come loose. I you are using a track you can place it on top of the gunnel (I placed stainless screws about 6 inches apart and one at each end of the track) I drilled very small pilot holes (as Jim stated) and then put a spot of 3m 5200 over each hole. The combination of the amount of screws and the 5200 will hold the track just fine. Do the same for the eyelets on the inside of the hull. I just redid my hull and the eyelets that hold my Bimini top have been in place since 1975(screwed to the inside of the hull). Like I said the trick is not pulling on the screws from the top, the force on the screws are from the side, they are much stronger this way. And having the eyelets at an angle (in-line) with the straps help also. I'll see if I can get you some pictures of my set up....Take care
Hoosier	posted 09-12-2010 07:34 AM ET (US) When I installed Bimini tracks on my Montauk I used a full length strip of auto trim tape on the bottom of the track, in addition to the screws. The tracks never moved or loosened.
nitro vinny	posted 09-12-2010 03:03 PM ET (US) Thanks for the 5200 and the auto trim tape pointers.